Phonological Abilities in Persian Speaking Preschool Children with Stuttering and Fluent Peers.

Objectives Speech sound production is poorer in stutterers than normally fluent peers. This study was performed to compare speech sound production abilities in Persian speaking children with developmental stuttering. Materials & Methods Overall, 34 children with stuttering and 60 children without stuttering aged from 3 to 6 yr old were enrolled from Ahvaz City, Khuzestan Province, southern Iran in 2016. The phonetic information test was used to assess speech sound production in this study and 30-minute mother-child conversations were utilized for calculation of Percentage Consonant Correct. Phonological abilities of these two groups were compared against each other and a correlation between stuttering severity and speech sound articulation was calculated. Results There was significant difference between children with stuttering and normal peers for articulation error total percentage but not significant difference was found for percentage consonant correct (P=0.16). Moreover, no significant correlation between stuttering severity and speech sound production in this population was found. Conclusion No association seems to exist between stuttering severity and speech sound production abilities in this population. This study may lead to the notion that there was significant difference between the two groups in speech sound production assessment.


Introduction
As a subtype of communication disorders (1), developmental stuttering is one of the speech fluency disorders manifested clinically by interruption in speech flow such as repetition, block, and prolongation (2). The prevalence of stuttering is estimated at less than 1% in the adult population (3) and 2.52% in preschool children in the US (4). Stuttering is a multifactorial disorder affected by different factors. Moreover, phonetic and phonological factors attracted attention to themselves in stuttering (5).
Postma and Kolk discussed theory on the production and phonological planning, which contributes to stuttering (6). This theory is consistent with some studies that report the rate of incidence of phonological disorders in children with stuttering is higher than normal peers (7,8). Children's phonetic and phonological development is very fast between the age of 2 to 4 and this range is considered as stuttering onset in the literature (9)(10)(11). Other communication disorders may comorbid with stuttering (12,13). Concomitant disorders complicate the communication process and cause children with stuttering to feel that communicating is difficult and exhausting.
A study was conducted on the comorbidity of other communication disorders in children with developmental stuttering. 16.8 of children with developmental stuttering, had articulation disorders too (12). The likelihood of phonological disorders is far more in children with stuttering than fluent peers (14)(15)(16)(17)(18), in contrast, there was no significant difference between children with stuttering and normal peers in articulation and phonological abilities (17,19). Studies in this field can be categorized into two groups. Early studies frequently performed by informal assessment tools, which reported that speech sound production in children with stuttering is poorer than normally fluent peers. More recent studies carried out by formal and standardized assessment tools not always demonstrated a significant difference between children with stuttering and normal peers (20).
Due to different results on speech sound abilities in children with stuttering and normally fluent peers and lack of such study for Persian children with stuttering, we decided to investigate and compare both the percentage of the correct consonant and speech sound production abilities in Persian preschoolers.

Participants
Participants were 34 children with stuttering aged between 3-6 yr from Ahvaz City, Khuzestan Omission, substitution and distortion are speech sound errors that frequently discussed in literature.

Percentage Consonant Correct
Thirty minutes of connected speech was recorded to calculate Percentage consonant correct (PCC) for each child (24). All of the speech samples were gathered in a quiet room by a microphone (micromic c520 with amplifier Henyh 802). Video camera (Sony HX200v, High-resolution camera) was used to record the video of the connected speech of the children.

Calculation of Stuttering Severity
All children with stuttering were video recorded for for the statistical analysis of the current study.
Kolmogorov-Smirnov test was used to investigate the normal distribution of the sample. After the normal distribution of the sample was confirmed, independent sample t-test was used to compare mean scores of two groups in speech sound production test and percentage consonant correct.
ICC was used to obtain inter-rater reliability between two examiners. Pearson correlation coefficient was used to compute the correlation between stuttering severity and total errors in PIT.
The significance level was set at (P<0.05).

Ethical Consideration
This study was approved by the Ethical Committee of Ahvaz Jundishapur University of Medical Sciences(Code: IR.AJUMS.REC.1394.109). All of the parents filled the informed consent form and all the participants assented to participate in this research. We explained to parents that connected speech of children who stutter will be video recorded. If any child did not cooperate with the examiner, he was eliminated from the study. Table 1 is related to the descriptive data of children's scores in sub-scales of SSI4.

Comparison between two groups
Comparison between groups for speech sound production Overall, 94 preschool children (34 children with stuttering and 60 children without stuttering) were allocated in two groups. The findings related to the stuttering group are provided in Table 2.
Regarding the reported sums for different types of speech sound production errors (distortion, omission, substitution and articulation error total) in terms of percentage for each of them, there was no significant difference between the two groups in the distortion percentage of the two groups.
However, there was significant difference between the two groups for substitution percentage, omission percentage and articulation error total percentage ( Table 2).

Comparison between groups for PCC
As shown in Table 3 there was no significant difference in PCC in the two groups.

Correlation
Correlation between stuttering severity and error articulation There was no significant correlation between the mean of errors in speech production and stuttering severity in group of children with stuttering(r=0.28,

P=0.1).
Correlation between Stuttering Severity and PCC scores There was no significant correlation between PCC and stuttering severity in group of children with stuttering(r=0.13, P=0.46).

Inter-rater Reliability
There was a high correlation between two examiners shown by ICC=0.939, Upper band= 0.982, Lower band with % 95 confidence interval.

Discussion
The aim of the present study was to investigate the comparison of speech sound production errors and PCC in a group of Persian children with stuttering and normally fluent peers and examine whether there is a correlation between stuttering severity and speech sound production error in children with stuttering group. Additionally, the possibility of a correlation between PCC and stuttering severity in Persian children with stuttering was explored. Furthermore, the current study aimed to compare the speech sound production between children with stuttering and normally fluent peers. This study showed that articulation error total percentage is higher in children with stuttering than normally fluent peers. This finding was in accordance with another study (12,27). Phonological and articulation disorders are more prevalent in this group than normal peers are. We only compared speech sound production errors in two groups and did not study the prevalence of speech sound disorders in this population. However, our findings are not in line with another study (20). In conclusion, we studied only speech sounds production skills and percentage consonant correct.
There are some procedures like phonological patterns, rating of intelligibility and stimulability measurement for assessment of phonological abilities. It is recommended to design researches for studying the phonological patterns, intelligibility and stimulability in this population.